1. Field of the Invention
The invention relates to a method of manufacturing a jet nozzle plate for ink jet printers by means of a combined press and punch operation with a press mould in the form of a plastics cushion, and also relates to a device for performing the method.
2. Description of the Prior Art
In order to obtain individual ink droplets, the ink jet printing head usually has a jet nozzle plate which includes at least one jet nozzle. The diameter of the jet nozzle is very small and amounts to approximately 50 .mu.m. The cross-section of the jet nozzle increases rotationally symmetrically in the direction of the side wherefrom the liquid is supplied in accordance with an exponential function in order to facilitate the supply of ink. The jet nozzle must have a smooth surface and sharp edges at the ejection side of the ink droplets. This surface is preferably formed to project from the surroundings. A tubular jet nozzle of this kind is known from U.S. Pat. No. 3,466,659 (German Auslesgeschrift 15 11 397.)
It is known to manufacture such jet nozzle plates by spark erosion, by drilling or by etching. Because the dimensions of the jet nozzles are in the micrometer range, these known methods do not offer the required precision. Either the inner walls of the jet nozzles are too rough or the edges of the discharge opening are not sharp enough. A pure stamping operation does not provide the desired dimensional accuracy either, because there is a risk of cracking of the discharge opening of the jet nozzle.